One of the obstacles encountered when studying nano-scale phenomena is the limited resolution of visible light. When dealing with solid or frozen materials, one can take advantage of the relatively small wavelengths of electrons to visualize phenomena at sub-nanometer length scales. Unfortunately, however, conventional electron microscopy requires vacuum conditions, and, in the past, this has precluded its use for the study of volatile fluids. With present day technology, at best, one can operate with environmental chambers that allow the introduction of humid gases. The conditions prevailing in the environmental chamber are very different from the ones experienced, for example, by biological molecules in aqueous solutions and catalytic reactions in general. This limits one's ability to carry out studies of biological interactions and chemical reactions under controlled conditions.
It is envisioned that experiments currently conducted with near field microscopy and total internal reflection (TIRF) microscopy can be duplicated with electron microscopy with much higher resolution than is currently feasible. The molecules to be observed can be tagged with particles, atoms, and possibly observed directly without a label. As a result, various reactions and interactions in liquid and gaseous environments may be studied.
A common method for the detection of particles and biological substances is to transmit the analyte through a small tube or pore and monitor the effect of the presence of the analyte on the ionic current. The presence of an analyte suppresses or blocks the ionic current. The magnitude of the blockage and its duration can be used to characterize the size of the analyte. To make the detection process specific, one can use functionalized carriers such as particles or known molecules that bind the analyte specifically and monitor the effect of the analyte on the characteristics of the carrier. The sensitivity of this biosensing technique depends on the size of the pore or tube. The small diameter of the nanotubes would facilitate the construction of high sensitivity devices.
Currently, pulled glass micropipettes are used to study the properties of cells and to exchange material with a cell's interior. These techniques are intrusive and typically limited to operating with a single cell at a time. There is a need for less intrusive probes.
Currently scanning probes allow one to probe the mechanical and electrical properties of samples. There is an unmet need for probes that can exchange fluids and molecules with the scanned sample.